Spinal cord stimulation (SCS), a widely used modality for the treatment of chronic pain, is also known to have a significant vasodilator effect on peripheral vasculature. Interest in the vascular effects of SCS has resulted in its use to treat both peripheral limb ischemic and angina. Similar effects of SCS on cerebral blood flow have also been suggested. However, the significance, character and underlying mechanisms of the cerebrovascular effects of SCS remain unclear. The accompanying proposal will delineate the cerebrovascular effects of SCS in an animal model and examine the mechanism(s) that may be involved. We will also examine the feasibility of using SCS in the prevention of cerebral infarction. Specifically, we will test the following central hypotheses: I. SGS significantly enhances global cerebral blood flow (CBF) II. Cerebrovascular effects of SCS are related to changes in sympathetic tone III. Cerebrovascular effects Of SCS involve activation of brainstem/cerebellar vasomotor centers IV. Trigeminovascular innervation of cerebral vasculature mediates SCS effects on CBF V. SCS has a neuroprotective effect in the setting of focal cerebral ischemic We will utilize an in vivo model of SCS and CBF measurement in rats in order to obtain information about the magnitude, time course, and spatial characteristics of CBF changes induced by SCS. Using this model, we will also investigate the effects of SCS on stroke induced by focal cerebral ischemic. An understanding of the mechanisms involved in the cerebrovascular effects of SCS has direct ramifications in the treatment of conditions where cerebral blood flow is compromised, such as stroke, cerebral vasospasm and traumatic brain injury.